Method of bulking yarns



April 1968 J. A. SPICER 3,378,900

METHOD OF BULKING YARNS Filed Feb. 23, 1966 lnenlor IF A. SPNZER "m -5%-Attorneys United States Patent 3,378,900 METHOD OF BULKING YARNS JackAlbert Spicer, Coventry, England, assignor t0 Courtaulds Limited,London, England, a British company Filed Feb. 23, 1966, Ser. No. 535,2832 Claims. (Cl. 28-72) ABSTRACT OF THE DISCLOSURE A yarn bulking processcomprising passing a plurality of low-twist, heat-settab'le, continuousfilament yarns between nip rollers and through a stufiing box in whichthe yarns are allowed a degree of lateral movement, heating the yarns atsome stage in their passage through the stufiing box, cooling the yarnsto set the crimp imposed on them in the stufiing box, stretching theyarns to separate the filaments in the yarns, and then relaxing theyarns, whereupon the filaments tend to revert to their crimped shapesand engagement of adjacent filaments with each other produces a bulkingefiect on the yarns.

This invention relates to the production of bulked yarns.

It is already known to produce crimped yarns and fibres by forcing themby means of positively fed rollers into a confined space, generallydescribed as a stufiing box, through which the yarns or fibres areforced against the friction of the walls of the box to emerge at the farend. In the box, the individual fibres or yarns assume a crimpedconfiguration and the extent to which this is retained in the yarn whichemerges can be enhanced by the application of heat to the yarn or fibrein the box.

According to the present invention a yarn bulking process comprisespassing a plurality of low-twist, heatsettable, continuous filamentyarns, parallel to each other and in a single layer, between a pair ofnip rollers into and through a stuffing box comprising a channel ofwidth such that the yarns are allowed a degree of lateral movement, theopen side of the channel being closed by a pressure plate, heating theyarns in or before entering the stufiing box, cooling the yarns to setthe crimp imposed on them in the stuffing box, stretching the yarns toat least 90 percent of their uncrimped lengths, thereby separating thefilaments in the yarns, and then relaxing the yarns, whereupon thefilament-s tend to revert to the crimped shapes imparted to them in thestuffing box, and engagement of adjacent filaments with each otherproduces a bulking effect on the yarns.

By low twist yarns we mean yarns with a twist of up to about 5 turns perinch. In practice the process is best applied to yarns having only aspinning twist, that is about /3 /2 turn per inch.

The term heat-settable as applied to yarns which may be bulked by theprocess, means that each yarn should contain a sufiicient proportion ofthermoplastic filaments for the yarns to be set in the shape imparted tothem during the process. Preferably the yarns consist wholly ofthermoplastic filaments.

Heating the yarns may be accomplished in or before they enter thestuffing box. With heavy denier yarns it may even be necessary to heatthe yarns both before and with in the stutfing box. When the stuffingbox is itself heated, this is generally accomplished electrically.Additional heat ing may be provided by admitting steam to the stufiingbox through apertures provided in the channel and/or the pressure platefor this purpose.

By virtue of the lateral spacing of the yarns in the 3,378,900 PatentedApr. 23, 1968 stuffing box, they are permitted to crimp laterally aswell as against the restraining force of the pressure plate, and thislateral crimping causes filaments of adjacent yarns to interfere witheach other, although the yarns themselves are prevented from overlappingand maintained in a single layer by the pressure plate. Thisinterference causes the adjacent yarns to cling together, and the yarnsare delivered from the stufiing box in the form of a flat ribbon. Onstretching the ribbon, the filaments are straightened out so that theinterfering filaments, and consequently the individual yarns, areseparated, and the yarns can then be relaxed and wound separately intopackages in their bulked state, or fed directly to subsequent processingequipment.

The stretching operation may be accomplished immediately after the yarnshave cooled or, if desired, the stretching operation may be delayed.Thus, in practice, it may be convenient to pack the ribbon of crimpedyarns delivered from the stutfing box directly into a box or bale andthen, when it is desired to bulk the yarn, the individual yarns can beseparated by drawing the ribbon from the box or bale through atensioning zone where the filaments are substantially straightened andthrough a relaxation zone.

By a plurality of yarns is meant at least two but the number may rise tothe limit of the number of yarns which can be controlled in the stufiingbox. There must not, of course, be so many yarns in relation to theWidth of the stufiing box that the yarns are .not allowed a degree oflateral movement. More than one layer of yarns, each layer comprising aplurality of yarns in side-by-side relation may be passed into thestufiing box if desired. By the suitable choice of the numbers of yarnsin each layer and by the superimposition of yarns in upper layers uponyarns in lower layers, a doubling effect is obtainable by keeping pairsor groups of superimposed yarns close together during the relaxation, sothat filaments of the adjacent yarns again tend to interfere to keep theyarns together, and the joined yarns may in fact be used without furthertreatment. Using this doubling eifect it is possible to obtain heavydenier yarns containing a large number of low denier filaments whichhave a much higher bulk than conventional heavy denier yarns containingfewer higher denier filaments. 1

Whilst the yarns must be stretched to at least percent of theiruncrimped lengths, it is preferred that they should be stretched by anamount in excess of this provided that they are not stretched to lengthsgreater than their uncrimped lengths as this removes some of the crimpin the filaments and can cause filament breakage.

An example of an apparatus for carrying out the process of the inventionis shown in the accompanying drawing, in (which FIGURE 1 is adiagrammatic elevation of a stufiing box and FIGURE 2 is a diagrammaticelevation of a yarn stretching apparatus.

In FIGURE 1, six yarns 1 are drawn from individual yarn packages 2 overa tension device, shown as two tension rolls 3 and are presented to thenip of .a pair of feed rollers 4 and 5 through a guide comprising anumber of upright comb pins 6 which separate each yarn from itsneighbour. The axis of the lower roller 4 is fixed and the upper roller5 is subjected to downward pneumatic pressure. The yarns are guided bythe positioning of the rolls 3 and guide pins 6 so that they are drawninto the nip of rollers 4 and 5 in a single layer, in side-by-siderelation, and are fed as a layer into a channel 7 which has electricheaters 8 in its base. The walls of the channel are smooth and the widthof the channel is wider than the sum of the diameters of the yarns, suchthat the yarns are allowed a degree of lateral movement in the channel.The open top of channel 7 is closed by a pressure plate 9 of T-shapecross-section, the limb of which is of width such as to fit closely butfreely between the walls of the channel and of depth somewhat greaterthan the depth of the channel. Electric heaters 10 are mounted on top ofthe pressure plate 9 and the plate is pivotally mounted by arms 11 uponthe shaft 12 of the upper roller 5. A yoke 13 spans the opposite end ofthe pressure plate 9 and the adjacent part of the channel 7 enablesweights 14 to be applied to it to vary the pressure on the yarn beingtreated. The yarns emerge from the end of channel 7 in the form of aribbon 15, adjacent yarns adhering slightly together and each of theyarns being crimped.

In addition to the electric heaters 8 and 10, preparation may be madefor steam heating the yarns passing through the crimping channel 7. Thisis particularly desirable for some yarns where the presence of moisturefrom the steam is advantageous in setting the crimp. For this purpose apipe 16 is provided, passing through the base of the channel 7 close toits end adjacent to the rollers 4 and so that steam may be passed intothe channel to permeate the yarns at this point.

In FIGURE 2 the ribbon of yarns 15, which may come directly from thestufiing box shown in FIGURE 1 or from storage, is drawn into the nip ofa pair of rollers 17 and is then passed to a second pair of rollers 18which are rotated at a higher surface speed than rollers 17 such thatthe yarns are stretched between the rollers to at least 90 percent oftheir uncrimped lengths. Between the pairs of rollers 17 and 18 is aguide comprising a num ber of comb pins 19 which separate the yarns inthe tow 15 so that they emerge as separate yarns 20 from rollers 18whereupon they are relaxed and collected into packages.

An apparatus as described above, having a crimping channel ofapproximately 13 long, measured from the axis of rollers 4 and 5 andhaving an internal width of 0.5" was used in the production of bulkedyarns as described in the following examples.

Example 1 Three nylon-6 yarns, each of 3000 denier and 4 turns per inch,were fed through the apparatus at a speed of 50 yards per minute withthe stufiing box heated to a temperature of 170 C. The crimped yarnsWithdrawn from the stuifing box as a ribbon were collected in a box andallowed to cool overnight in a conditioned atmosphere. Subsequently, theribbon was withdrawn from the box, passed over a lick-roller, for theapplication of an antistatic agent and a lubricant, stretched betweentwo pairs of nip rollers to about 95 percent of the uncrimped length ofthe yarns and then relaxed and the separate yarns were collected oncones. The yarns were highly bulked and a tufted loop-pile carpet madeusing the bulked yarns in the pile was found to have excellentproperties.

Example 2 The procedure of Example 1 was followed with the exceptionthat the three nylon-6 yarns were replaced by thirty 70 denier 0.5t.p.i. yarns which were fed to the stuffing box as three layers each ofyarns. The yarns in the middle and the top layers were superimposed onthe appropriate yarns of the bottom layer by using a guide having 10slots, through each of which one yarn from each layer was passed. Thespeed of the yarns through the stufiing box was increased to 500 yds.per minute.

During the stretching operation the tow or ribbon of yarns was separatedinto 10 yarns, each formed from three of the original yarns, which wereindividually collected. A sock knitted from one of these yarns was foundto be equivalent in bulk and weight to a sock of similar constructionmade from 4 ends of a false-twisted yarn of the same type.

Example 3 The procedure of Example 2 was followed with the exceptionthat the 30 yarns were replaced by 10 yarns each of 200 denier. The tenyarns formed a single layer.

Example 4 The procedure of Example 2 was followed with the exceptionthat the three layers each of 10 yarns were replaced by 18 layers eachof three yarns. The product of this example was a heavy denier bulkedyarn having a very large number of filaments.

Example 5 The procedure of Example 1 was followed except that the yarnsused were 1000 denier yarns of an acrylonitrile/ vinylidene chloridecopolymer.

The products of all the examples had two particular advantages overyarns produced by false-twisting in that the yarns had no twist-bias andhad small extensibilities.

What I claim is:

1. A yarn bulking process comprising passing a plurality of low-twist,heat-settable, continuous filament yarns, which are parallel to eachother and in a single layer, between a pair of nip rollers, into andthrough a stufiing box of a width such that the yarns are allowed adegree of lateral movement, and having a transverse wall which isdefined by a pressure plate which is maintained parallel with theopposite transverse wall, heating the yarns at some stage in theirpassage into and through the sutfling box, cooling the yarns to set thecrimp imposed on them in the stuffing box, stretching the yarns to atleast percent of their uncrimped lengths, thereby separating thefilaments in the yarns, and then relaxing the yarns, whereupon thefilaments tend to revert to the crimped shapes imparted to them in thestulfing box and engagement of adjacent filaments with each otherproduces a bulking effect on the yarn.

2. A process according to claim 1 wherein a plurality of layers ofyarns, each layer comprising a plurality of yarns, are fed to the niprollers, superimposed yarns being kept close together during therelaxation, whereby the filaments of the adjacent yarns tend tointerfere to keep the yarns together.

References Cited UNITED STATES PATENTS 3,022,545 2/1962 Wylde et al 19-66 3,044,145 7/1962 Tager 281 3,099,064 7/1963 Haynes 281 3,298,079l/1967 Ageth et al. 28-72 3,325,874 6/1967 Edney 28---1 3,340,585 9/1967Buckley et al.

LOUIS K. RIMRODT, Primary Examiner.

